A case of a 44 year old man with a duodeno-colic fistula secondary to an adenocarcinoma of the second part of the duodenum is described. An asymptomatic leiomyoma of the second part of the duodenum was also present. The patient had been treated successfully for a right Wilms' cancer in childhood with surgery and radiotherapy. There are no previous reports of a duodenal carcinoma arising following a Wilms' tumour and cases of gastrointestinal adenocarcinoma arising as second malignancies following Wilms' tumours are reviewed. The aetiology of duodeno-colic fistulas is reviewed. Duodenal carcinoma is a unusual cause of duodeno-colic fistulas and this case may be unique in that respect.